Apart from tubular semimanufactured articles made from narrow plastic tapes and fabricated on circular looms, tubular plastic film made from a softenable thermoplastic manufactured by extrusion machines, are also employed in the manufacture of packing sacks, large-volume container sacks and other receptacles.
So that that such receptacles will have the necessary carrying strength, the reinforcement technique employed in the fabrication of hoses has basically been adopted.
Accordingly, it is customary with newer processes to reinforce an extruded tubular film of thermoplastic with narrow strands or tapes made from plastic, extending, for example, helically around the circumference of said first extrudate. Then a second tubular film of thermoplastic may be applied in co-extruding manner as a covering or jacket.
Seen from the point of view that such processes serve the mass production of finished products, a significant disadvantage results here owing to the high consumption of material which results on the co-extrusion of said outer jacket film due to the inevitable thickness of the wall of said tubular extrudate, although from the strength of such finished products, the wall strength of said jacket film could be somewhat less.